In general, a floating support has anchor means to enable it to remain in position in spite of the effects of current, wind, and swell. It generally also includes means for storing and processing oil and off-loading means for use with off-loading tankers, where such tankers call at regular intervals to remove the production. Such floating supports are commonly referred to as floating production storage off-loading (FPSO) units.
Floating supports are:                either of constant heading type, i.e. they possess a plurality of anchors, generally situated at each of the corners of said floating support and serving to keep it on a heading that cannot vary, leaving it free to move only in roll and in pitching and limiting any movement in surge and yaw;        or else of the turret type, i.e. all of the anchors converge on a cylindrical structure secured to the ship, but free to rotate about a vertical axis ZZ′, thus leaving the floating support free to turn around said turret and position itself in the direction of least resistance for the resultant of the effects of wind, current, and swell on the floating support and its super-structures.        
Constant-heading type floating supports are intended for use more particularly in environments that are not too rough and that present swell of medium amplitude coming from a single direction, as applies in West Africa. The floating support is then installed facing the prevailing swell direction in order to minimize its effects. That type of floating support presents the advantage of enabling a very large number of bottom-to-surface connections to be installed simply over one side of said floating support, or indeed over both its starboard and port sides.
However, when conditions are more severe, or indeed extreme as in the North Sea, WO 2009/150142 proposes a constant-heading type floating support, namely a platform of the spar type having a bottom structure that is disconnectable to which the top ends of hoses are connected that provide bottom-to-surface connection. However, for those extreme conditions, an advantageous floating support is then of the turret type, with all of the bottom-to-surface connections converging on a turret prior to extending to the FPSO proper, via a swivel joint connection situated on the axis of said turret. In general, the bottom-to-surface connection pipes are constituted by flexible hoses directly connecting pipes resting on the sea bottom to the turret, said hoses generally being organized radially or in a star configuration so as to be uniformly distributed around the axis of said turret.
Numerous configurations have been developed, and reference may be made to patent WO 2009/122098 in the name of the Applicant which describes an FPSO fitted with such a turret and associated flexible hoses, more particularly for use in the extreme conditions that are to be encountered in the Arctic. Such a configuration is advantageous for medium depths of water, i.e. lying in the range 100 meters (m) to 350 m, or indeed in the range 500 m to 600 m. In particular, using hoses over the full depth of the body of water between the rigid pipes resting on the sea bottom and the floating support allows the floating supports to move more than would be possible if rigid pipes were used. Nevertheless, with that type of bottom-to-surface connection between the turret of a floating support and pipes resting on the sea bottom, it is not possible to use said hoses in a dipping catenary configuration, i.e. with a low point of inflection as described for hybrid tower type bottom-to-surface connections that comprise:                a vertical riser having its bottom end anchored to the sea bottom via a flexible hinge and connected to a said pipe resting on the sea bottom, and having its top end connected to a float immersed in the subsurface and serving to tension the riser; and        a connecting flexible hose between the top end of said riser and a floating support on the surface, said connecting flexible hose possibly taking up under the effect of its own weight the shape of a dipping catenary curve, i.e. a curve that goes down well below the float and subsequently rises up to said floating support, which dipping catenary is capable of accommodating large amounts of movement of the floating support, with this being absorbed by deformation of the flexible hose, in particular by raising or lowering said low point of inflection of the dipping catenary.        
However, as soon as the water reaches a depth lying in the range 1000 m to 1500 m, or indeed 2000 m to 3000 m, the cost of such a multitude of flexible hoses becomes very high because of the developed length of each of said hoses, since hoses are very complex and very difficult to fabricate if they are to achieve the levels of safety in operation that are required to enable them to remain in operation over periods of time that may reach or exceed 20 years to 25 years, or even more.
In particular, the hoses run the risk of interfering with one another and of banging against one another.